Friction-facing and process of making same.



UNITED isrnrns PATENT orrron.

LEsrEn mscnnnnun, ornvnnsron, ILLINOIS, ASSIGNOB TO THE RAYIBESTOS comrm, or nnmenronr, comrncrrcnr, A conrona'non or comcrrcnr.

rmcrron-recme aivnrnocnss or MAKING sum.

No Drawing.

To all whom it may concern: Be it known that I, LESTER a citizen of the United the city of Evanston, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Friction Facings and Processes of Making Same, of which the following is a specification. This invention relates to improvements friction facings and process of making same, and refers more particularly to a friction facing adapted for'use in motor cars and the like. 7

Among the salient objects of the invention are to provide. a product which in its entirety is or can be made of substantially incombustible materials, at least, inoombustible attemperaturesto which clutch facings, brake lin'nigs and the like are subjected in use; to provide a process in which the friction facing can be formed into an unwoven felted sheet made from relatively short asbestos fiber to which strength or body is given by the addition of a substantially incombustible material; to provide a rated and impregnated with a bituminous or hydrocarbon binder prior to the felting operation; to provide a process in which the binder is incorporated into the asbestos at or before the felting operation; to provide a process which can be carried out as a cold process and which eliminates the necessity of the use of; expensive vehicles in the satu-,

rating operation, and in efi ect eliminates an independent saturating operation altogether; to provide a process whichpermits of the use 'ofhigh melting point binders which are more refractory and cementitious than the binders now in use for this purpose and in general to provide an improved process and product of the character described.

I am aware that heretofore there has been invented an 'unwoven friction facing made from short asbestos fiber but as far as I know this short asbestos fiber has nevertheretofore been saturated or incorporated with the binder during the pulping operation or prior to-the felting.

-Describing now .the improved product and process of making the same, 1E first make Specification of fett r; Patent.

KIRSCHBRAUN, States, residing in Patented Aug. 6, 191a.

Application filed May 27, 1918. Serial N 0. 236,957.

an emulsion, of a bituminous binder and an colloidal emulsifying i agent, preferably clay, starch, cheap glue, casein or cheap soap. colloidal-clay or other inorganic colloidal .material is that it is inexpensive and incombustible. The clay, or other filler which glS used as an emulsifying agent is made into an aqueous paste and then melted bitumen or hydrocarbon is gradually added and stirred into the filler until a homogeneous composition results. W,hile the hydrocarbon is being gradually added to the aqueous paste hot water is also preferably added from time. to time to maintain the desired working consistency. This emulsified .com-

position thinned to the desired consistency by the addition of water'is mixed with the short asbestos fiber either before or after the latter is pulped; The mass is mixed to- The advantage however, of using gether until the filler and binderhave become thoroughly amalgamated with the as-- bestos fiber. By adding the binder to this compound the asbestos fibers become thor oughly coated with the binder.- The pulpedi mass may have more water added to it or the excess water removed from it as condi; tion may require to produce the desired working consistency, and the material is now ready for felting.

Ordinarily, in the felting operation of fibers, they are held together by a mechanical bond due to the interlacing of the fibers.

In the felting mixture heretofore described however, the fibers are already coated with a bituminous binder so in felting this miX- ture you not only get a mechanical bond due to the interlacingof the fibers but an additional bond due to the adhesion of the bituminous binder coating of the individual fibers. In the felting operation the particles of clay, if clay is used as a filler, are forced into and fill the voids between the fibers and thereby add density, body and strength or toughness tothe sheet.

After the felting operation, the sheet may be passed over steam heated rolls so as .to 'drive the water out. or if desired may be put into a drying room to eliminate the moisture. Tlie removal of the water or moisture from the bitumen transforms it fromthe state of an emulsion'to that of a of which consists of an a bituminous binder and a relatively incombustible filler, the filler and binder being in colloidal relation to each other.

3. The process of making a. friction facvl5 ing consisting in emulsifying a filler and a bitumen to form an emulsified composition, mixing said composition with an incombustible fiber and intimately commingling said fiber with said composition to'form said last 20 mentioned mixture into a. felted unwoven sheet and drying the same to moisture therefrom.

LESTER KIRSCBBRA UN.

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